
where in general KK numbers within parentheses (the \((i)\) ) refer to those of the spin-0 states, while those without parentheses (the \(j\) ) reference the spin-2 states. We expand the matrix element \(\mathcal {M}\)  in a
Taylor series in \(s\)  as [1]},
\(\mathcal {M}(s,\theta ) = \sum _{\sigma \in \tfrac{1}{2}\mathbb {Z} } \overline{\mathcal {M}}^{(\sigma )}(\theta )\cdot s^{\sigma }\) 
